Research Interests

Solar Energy Conversion, Organic Photovoltaics, Artificial Photosynthesis, Porphyrin Synthesis and Spectroscopy, Self-Assembly, Photodynamic Therapy, Dendrimer synthesis, Electron-Transfer Reactions, Time-Resolved Laser Spectroscopy, Photophysics and Photochemistry.

My group combines synthetic chemistry with ultrafast laser spectroscopy to study the electronic properties of molecules, self-assembled materials, and polymers. The properties of both molecules and, in particular, supramolecular assemblies are strongly influenced by subtle changes in structure. Our work involves understanding these electronic properties from a physical organic and materials point of view. 

Synthesis and Ultrafast Time-Resolved Spectroscopy of Organic Photovoltaics  
Photovoltaic devices (PDs) are designed to convert solar energy into electricity.  Our research on organic PDs is focused on developing new paradigms in PD design by synthesizing self-assembled electron-donor and electron-acceptor arrays.  We use ultrafast laser spectroscopy on the femtosecond and picosecond time scales to study energy and electron transfer in these compounds.  The results from these experiments are translated into preparing new organic PDs.

Electron- and Energy-Transfer in Self-Assembled Materials
A second area of research in our group is the synthesis, study, and time-resolved spectroscopy of self-assembled materials. The covalent synthesis of complex molecules is time-consuming and quite expensive. Mother Nature has solved this problem by synthesizing small molecules and using non-covalent interactions to self-assemble them into more complex architectures. A major area of research in our group involves the synthesis of small molecules containing chromophores that can be self-assembled using hydrogen-bonding and other non-covalent interactions into complex 3-D structures. We characterize these assemblies using various morphology techniques (TEM, SEM, AFM), and then study the photodynamic processes occurring with ultrafast electronic excitation.

Electron-Transfer in Photosynthetic Reaction Center Mimics 
The photosynthetic reaction center in green plants and purple bacteria utilizes light to initiate a series of electron-transfer steps that transports an electron over extremely long distances. A third area of research in our group involves the synthesis and study of photosynthetic mimics, that is, nanoscale molecules that are designed to replicate the complex and elegant process of electron-transfer in biological systems. The photosynthetic mimics synthesized and studied in our research group are based upon dendrimers that  contain porphyrins or porphyrin analogs at the core of the dendrimer and electron acceptor groups as end-groups.

Photophysical Properties of Unusual Porphyrins and Porphyrinoids  
My group also synthesizes and studies the optical properties (steady state and ultrafast time-resolved) of unusual porphyrins and porphyrinoids.  In particular, we are interested in using the tautomerism inherent to certain classes of porphyrins to influence excited state chemistry.

Selected Publications

1. Alemán, E.A.; Joseph, J.; Modarelli, D.A. "Solvent Effects on the Absorption Properties and Tautomerism of N-Confused Tetraphenylporphyrin" J. Org. Chem. 2015, 80, 11031−11038. DOI:10.1021/acs.joc.5b02244. 
2. Mehr, H.S.; Romano, N.C..;Altamimi, R.; Modarelli, J.M.; Modarelli, D.A. "Core-Substituted Naphthalene Diimide - Metallo Bisterpyridine Supramolecular Polymers: Synthesis, Photophysics and Morphology" Dalton Transactions 2015, 44, 3176-3184. 
3. Liu, H.; Espe, M.; Modarelli, D.A.; Arias, E.; Moggio, I.; Ziolo, R.F.; Heinz, H. "Interaction of Substituted Poly(Phenylethynylenes) with Ligand-Stabilized CdS Nanoparticles" J. Mater. Chem. A 2014, 2, 8705 – 8711.
4. Tu, S.; Kim, S.H.; Joseph, J.; Modarelli, D.A.; Parquette, J.R. "Proton-Coupled Self-Assembly of a Porphyrin Naphthalenediimide (NDI) Dyad" ChemPhysChem 2013, 14, 1609 – 1617.    
5. Wang, C.-L.; Zhang, W.-B.; Yu, X.; Yue, K.; Sun, H.-J.; Hsu, C.-H.; Hsu, C.-S.; Jospeh, J.; Modarelli, D.A.; Cheng, S.Z.D. "Facile Synthesis and Photophysical Properties of Sphere-Square Shape Amphiphiles Based on Porphyrin-[60]Fullerene Conjugates" Chem. Asian J. 2013, 8, 947 – 955.  
6. Acharya,Rajendra; Paudel, Liladhar; Joseph, Jojo; McCarthy, Claire E.; Dudipala, Venkat R.; Modarelli, Jody M.; Modarelli, David A. "Synthesis of Three Asymmetric N-Confused Porphyrins" J. Org. Chem. 2012, 77(14), 6043–6050.
7. Hassan, Mohammad L.; Moorefield, Charles M.; Elbatal, Hany S.; Newkome, George R.; Modarelli, David A.; Romano, Natalie C.  "Fluorescent cellulose nanocrystals via supramolecular assembly of terpyridine-modified cellulose nanocrystals and terpyridine-modified perylene"  Materials Science & Engineering, B: Advanced Functional Solid-State Materials 2012, 177(4), 350-358.
8. Tu, S.; Kim, S.H.; Joseph, J.; Modarelli, D.A.; Parquette, J.R. "Self-Assembly of a Donor-Acceptor Nanotube. A Strategy to Create Bicontinuous Arrays" J. Am. Chem. Soc. 2011, 133(47), 19125-19130.
9. Alemán, E.A.; Manriquez Rocha, J.; Wongwitwichote, W.; Godinez Mora-Tova, L.A.; Modarelli, D.A. "Spectroscopy of Free-Base N-Confused Tetraphenylporphyrin Radical Cation and Radical Anion" J. Phys. Chem. A 2011, 115, 6456–6471.
10. Shao, H.; Seifert, J.; Romano, N.C.; Gao, M.; Helmus, J.J.; Jaroniec, C.P.; Modarelli, D.A.; Parquette, J.R. “Amphiphilic Self-Assembly of an n-type Nanotube”, Angew. Chem., 2010, 49, 7688 –7691. November Cover Page. 

    Also, recently submitted papers:

    Manandhar,E.; Ji,M.; Altamimi, R.; Parquette, J.R.; Modarelli, D.A. “Self-Assembly of Guanidinium-Substituted 1,4,5,8-Naphthalenediimides with Pyrophosphate, and Adenosine Phosphates” J. Org. Chem. 2016, submitted.